


to the end of the line

by cherriedpeaches



Series: Arumika Week 2019 [5]
Category: Shingeki no Kyojin | Attack on Titan
Genre: Alternate Universe - Modern Setting, Arumika Week, Captain America AU, F/M, Grief/Mourning, Human Experimentation, Kidnapping, Military Training, Mutation, Super Soldier Serum, Time Skips
Language: English
Status: In-Progress
Published: 2019-09-27
Updated: 2019-09-27
Packaged: 2020-10-29 10:56:29
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 2,020
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20795516
Author URL: https://archiveofourown.org/users/cherriedpeaches/pseuds/cherriedpeaches
Summary: Mikasa held it with both hands, staring down at the blank surface. It felt balanced, weighted. The people who made this knew their stuff.“Okay,” she said curtly. “I'll take the shield.”(A Captain America AU.)...Arumika Week, Day 5: Time-Skip





	to the end of the line

A serum.

They had a needle full of  _ something _ that they were going to  _ inject into her. _

The doctor (not Grisha, no, he was off to the side, watching and waiting) gave her a tight smile, tighter than the gloves he was wearing, but Mikasa didn't take her eyes off the glinting needle.

_ No, no, no, no. _

She glanced over to Eren, who was sitting on the bed next to her, sleeve rolled up and brow furrowed. His free hand was clenched, like he was struggling not to deck the doctor about to plunge an unknown substance into his bloodstream.

Mikasa felt the same.

(If she'd looked a little closer, a little less distracted by the look on Eren's face, she would've seen that Eren's serum was slightly different. A little thicker, tinged a little green.

Different formula, different results.)

A murmur passed through the doctors to the side, and Mikasa forced herself not to look for Grisha. She didn't look at the serum, she didn't look at her arm, she just focused on Eren, a lone trustworthy face in a crowd of strangers in gloves and masks.

_ Get away from me, get away, get away— _

The needle pricked her arm.

Mikasa saw Eren slump over next to her, a moment and a half before everything blinked out.

* * *

The process, as it turned out, was not slow.

The doctors, as Mikasa had overheard in hushed whispers throughout base corridors and hallways of her own house, had theorized that it would take a while to reach full potential. The body has to adjust, they said.

It didn't.

Mikasa fell asleep a lightly underfed fifteen-year old girl. (Rations were tight in war times. That's what Grisha always said.) Admittedly, she had been a little tall and bulky for her age, stronger than she looked (and highly aggressive according to the neighborhood bullies), but that was nothing to what she was  _ after _ the serum.

Mikasa woke up almost half a foot taller, frame wrapped in muscle. She had  _ abs. _

“So, you get ripped,” Eren said one day, when they were still locked in the secret base that they had been (experimented on) given the serum in. “And I get... what? What did they do to me?”

Two days later, they had to take some tests. Physical tests.

Mikasa was given the standard ones. Endurance, strength, agility, all normal soldier training that she would have taken had she been able to join the war effort.

Unsurprisingly, she was stronger, faster, and more durable after practically gaining her previous body weight in pure muscle overnight. The doctors muttered a lot, took some notes on a clipboard, and moved onto Eren.

That was where it got  _ (horrifying) _ interesting.

The first thing that they did was ask Eren to lift a weight. Not just any weight. A massive, dense, hunk of metal that couldn't have weighed less than three tonnes.

Mikasa didn't think that  _ she'd _ be able to move it, and Eren was positively scrawny next to her.

Eren frowned, but tried it out anyway. He gripped the blunt edges of the massive lump and tried to lift. Nothing budged.

Eren tried again, and again, straining and pulling from different angles, but the rock didn't shift. The only sound was the murmurs of the (scientists?) doctors as they scribbled down notes, and the scrabbling of Eren's fingertips against the harsh metal.

Mikasa scanned the emotionless crowd of doctors, looking for Grisha's face. Searching for the familiar flash of round glasses or dark hair, but there was nothing.

_ He wasn't there. _

Grisha signed his son and pseudo-adopted daughter up for mutation and experimentation and isolation and then he hadn't even showed up to watch the results.

Mikasa wished that Armin was here. He'd say something clever that would convince the doctors to let them both go for the day.

Eventually, Eren stepped backwards and clenched his fists, looking positively furious in his defeat.

“Give me a second,” he hissed through gritted teeth, “I can—”

One of the doctors held up a silencing hand, and Eren flushed an even more outraged red. Another murmur swept through crowd, and a different doctor stepped forward, pulling down her mask.

“We'd like to try something different,”

Several people dressed in white crowded around Eren, and a surge of panic clawed up Mikasa's throat as she lost sight of him. She stepped forward, almost without realizing it, reaching to pull back one of the doctors.

“Step away, child,” one of them warned, a horrible, pitying look on their face that only accentuated Mikasa's nerves.

Mikasa opened her mouth, to argue or to yell or to fight, but the wall of white around Eren dispersed, and most of them stepped back, leaving only two doctors left by Eren's side.

One of them was holding his arm out, but not as if to keep him from running away.

The other was holding something sharp and glinting, standing right in front of Eren's arm. Something in Mikasa coiled up in horror and anger, oh God, it was another needle, hadn't they been through enough—

It wasn't a needle. It was a scalpel.

In one, fluid movement, the doctor slashed into Eren's arm.

There was three seconds of silence. Everyone stared for a moment as, slowly, blood began to leak out of the gash. Blood dripped onto the floor with a tiny splatter.

Mikasa stepped forward again, more forcefully, face hot with anger. She reached out, as if to grip at the lapels of the man with the scalpel, but a stronger force ripped her backwards. Her skin felt too tight and restraining, and she resisted the urge to thrash around in the grip of whoever was holding her.

The two people in white who had stood next to Eren stepped back, almost tripping in their hurry.

“Eren,” a deeper voice than the one before, strong and booming. “Your goal is to lift that weight.”

Eren flashed the sea of onlookers a look so full of hate that a few of them actually stepped back, fear written over their previously blank expressions. Then...

It was what Mikasa could only have imagined had happened to her after they injected the serum. Eren began growing, so quickly it looked like an optical illusion, limbs becoming thicker and shoulders widening, teeth baring, jaw strengthening.

But Eren  _ kept  _ growing, far bigger than Mikasa was, far bigger than any human should or  _ could _ ever grow. The white, expressionless shirt that they had both been dressed in ripped with a sudden  _ crack, _ falling to the ground as useless strips of fabric.

(The pants seemed to be made of a more flexible elastic, thankfully.)

Eren finally stopped growing once he was twice as tall as a normal human and three times as wide. He opened his mouth, (even his teeth seemed bigger, _ how did they do that?) _ and  _ roared. _

Mikasa saw red.

She began to claw at the hands on her shoulders, trying to rip herself out of their grip even as more hands seemed to join in on holding her back. For a split second, and  _ only _ a split second, she thought she might cry.

(She didn't, though. She doesn't cry for a long time.)

_ What did you do to him? _ She wanted to scream at the people in the white clothes. They kept scribbling on their clipboards, chattering among themselves, the way schoolchildren do when they're taking notes down from the blackboard.

Mikasa swallowed, struggles slowing down as Eren (giant and monstrous,  _ what did they do to him) _ took steps towards the chunk of metal. His footfalls reverberated around the massive (warehouse?) chamber that they were in, shaking the ground itself.

He plodded over to the weight, found his grip around the edges, and lifted.

Despite Mikasa's fury, it was breath-taking to watch.

Huge, bulging muscles rippled around his back and arms. Mikasa, in a faraway part of her mind, remembered Armin reading aloud a book about wild bears once.

_ Pure muscle. _

And Mikasa watched, with something akin to morbid fascination, as  _ (Eren) _ this giant lifted thousands of pounds of metal with one echoing grunt.

Then he dropped it with a cement-cracking thud.

For a moment, Mikasa thought that she was seeing things, mind hazy with disbelief and  _ (grief?) _ horror, but Eren began to shrink.

The enormous muscles just began to dissolve into thin air, into steam, boiling, blistering hot steam that Mikasa could feel from metres away. He wilted like a flower, mostly obscured by the massive amounts of vapor that his body was producing.

A good chunk of the scientists rushed over to investigate, but Mikasa was quicker this time. She snapped out of the hold of the people gripping her (slack with awe) and burst through the crowd of doctors, Eren in the centre.

He was on his knees, eyes closed, swaying gently, a stalk of corn in a slight breeze. Mikasa rushed over.

She knelt on one knee in front of him, gripping him by the shoulders, and shook him lightly. Immediately, several pairs of hands tried to wrench her backwards, but she held tight.

“Eren?” Mikasa asked, fingertips going white with the force of her grip. “Eren, are you alright?”

His eyelids flickered. “Mik'sa?”

She nearly collapsed.

An explosion of voices overtook theirs, all talking over each other and punctuated by the ever-present scratching of note-taking. “Eren, can you tell use your full name?” “Eren, can you tell us how old you are?” “Eren, do you remember anything from the last five minutes?” “Eren, does anywhere hurt? Did the excess steam cause any burns?” “Eren—”

_ “Shut up.” _ Mikasa rarely raised her voice above a low monotone, but something snapped inside her. These people had forced Eren to take on, and then lose hundreds of pounds of muscle in less than five minutes, and afterwards they couldn't even let him breathe for thirty seconds?

She forced herself to shut her eyes and count to fifteen, loosening her vice-grip on Eren's shoulders, but definitely not letting go.

“May we be excused for the day?” She asked quietly, looking back at the scientists crowding them. “I think he's been through enough.”

Several huffs of disagreement rang through the group, but one  _ (strange, familiar-faced)  _ man in particular held a hand up. He stepped forward, and everyone else parted respectfully around him.

“You may leave,” he said, and Mikasa recognized his voice as the booming one from earlier. “Head to your room and rest up, tests will resume tomorrow.”

Mikasa nodded. As she was slinging Eren's arm over her shoulder (he was surprisingly light when he was... normal) and getting to her feet, she glanced back up at the man's face, struggling to place him. Perhaps Grisha had a picture of him around the house, given how much authority he seemed to have.

No.

The man had come to dinner with the Jaegers, once. Years ago, when Mikasa could only have been nine or ten at the time, still quiet with grief over her parents. He'd been... a family friend? Kruger.

Eren Kruger.

Mikasa clenched her free hand so tightly that she could feel her nails digging grooves into the calloused skin of her palm. She took a second to just stare up at the man, an emotion, hot and liquid, filling her rib-cage and squeezing her insides.

_ (Anger? Betrayal?) _

How long had Grisha been planning to hand them over for experimentation? Had it been since the first time Kruger came over for dinner? Had he heard about Eren and Mikasa murdering three grown men in self-defense and immediately thought to subject them to tests?

(Or perhaps this had been planned since before either of them were born. Perhaps Grisha had had a child, always knowing that one day he would hand him off to a group of cold, white lab-coats, ready to be injected and cut open and treated like less than a dog.

Perhaps Mikasa had just been an add-on.)

She pulled herself to her feet, shifting Eren's weight accordingly, and walked off, head held high, avoiding eye contact with any of the strangers around her.

Beside her, Eren groaned.

**Author's Note:**

> I PULLED A SNEAKY ON YA
> 
> this one is definitely gonna be angstier than... probably every other prompt i've done for this week, combined. 
> 
> **IMPORTANT NOTE:** i have never seen any captain america movies (aside from like, 2 scenes from civil war) and don't plan to. this is just to be based very, very LOOSELY on what i've heard happens in the movies. i know steve rogers willingly signs up to be experimented on, i know his transformation process is very different, but this is a vague interpretation of mr. america's backstory.
> 
> dw, our boy armin is going to be showing up soon.
> 
> hmu on tumblr, i'm @brightwritesstuff


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